DEPARTMEXT OF ASTRONOMY AND COSMICAL PHYSICS 499 



2. On the Connection between Didurbed Areas of the Solar Surface and 

 the Solar Corona. By the Rev. A. L. CouTiE, *S'./., F.R.A.S. 



The general counection between the state of disturbance cf the sun's surface 

 and a particular type of solar corona is well established. The similarity of the 

 photographs of the solar coronse of the years 1 870, 1882, 1893, 1905 is very marked. 

 These were years of maximum solar activity, with many and great outbursts of 

 spots and prominences. Whether the spots or the prominences are the more inti- 

 mately connected with the streamers which constitute the characteristic forms of 

 the maximum type of corona is open to question. In the Stonyhurst photographs 

 of the corona of 1905 August 30, tlie streamers seemed in general to mark the 

 regions of pi-orainences rather than those of the sun-spots. Also, the complicated 

 structures of arches with vortex rings in the lower corona were attached to the 

 prominences. The sun-spot zones were marked by some straight bright rays in 

 the south-west quadrant, and by a set of beautiful plumes in the south-east quad- 

 rant. In the discussion of the results of the eclipse presented to the lioyal Irish 

 Academy it ' was shown that the area on the sun's surface to which these plumes 

 seemed to converge was situated in the south-east quadrant, at mean latitude, ap- 

 proximately - 21° S. The latitude of the largest of the four sun-spots visible on the 

 day of the eclipse was - 20° S., and this spot area was removed some 4 1° from the sun's 

 east limb. On the invisible side of the sun, removed about 51° from the limb, and 

 in latitude - 16° S., sufficiently near to the convergence latitude of the plumes, was 

 placed the area that had been the seat of the great February spot of 1905, the 

 greatest seen for thirty years. If the plumes converged behind the visible disc, it 

 was possible that they were connected with the area of disturbance of the Feb- 

 ruary spot ; if to an area on the visible hemisphere, thej^ would converge to a posi- 

 tion occupied by the largest spot of the day of eclipse, and formerly occupied by a 

 spot visible to the naked eye during July. Since writing the paper for the ' Trans- 

 actions' of the Royal Irish Academy the life-histories of the spots and faculso 

 occupying these two regions have been carefully studied from the Stonyhurst 

 drawings. The region of tlie great February spot was disturbed from January 5, 

 1905, to July 14, mean longitude 330°, latitude - 16°, but after the latter date became 

 quiescent, and remained so during the eclipse. But the region of the July spot, 

 and the spot of the day of eclipse, was disturbed from May 11 to August 30, 

 covering the j)eriod of eclipse. Therefore the connection, if any, wns between the 

 coronal plumes and this disturbed area. The connection seems probable, and more 

 than a mere coincidence, from the study of a similar region in 1893, which, as 

 shown in the Greenwich photographic results, was intermittently disturbed from 

 March 15 to November 16, and coincided in position (longitude 45°, latitude - 8° S.) 

 with a similar structure in the lower solar corona as described by Professor Schae- 

 berle in the report of the total solar eclipse of April 16, 1893 ('Contributions 

 from the Lick Observatory,' No. 4, p. 100). 



3, Telescopic Observations of Meteorolo(jical Phenomena. 

 By Miss C. 0. Stevens. 



The writer drew attention to the fiict that the ' boiling ' definition, so dis- 

 turbing to progress and accuracy of astronomical observations, is in itself a 

 phenomenon of great interest and value as an index of meteorological conditions. 

 It is better to be studied by means of a projected telescopic image of the sun than 

 by observation of moon, planets, or the stars. By careful analysis the movements 

 of 'boiling' are found to bear a definite relation to the prevailing drift of the 

 atmosphere, both in respect of direction and amplitude of movements. Two 

 distinct elements of distortion are displayed by the drift of any given stratum of 

 atmosphere across the sun's disc. This fact makes it possible to distinguish 

 between over-lying strata (travelling at an angle to one another) even in the 



• Trans, llmj. IrUh Acud , vol. xxxiil., section A, part 1. 



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